Okay, we aren’t talking literally on fire. We’re talking about the construction toy category that is having a very strong year, despite the economy and despite the popular, though incorrect, notion that kids only want to play with electronics.

LEGO bricks have always been a kids’ favorite over the years. First introduced in the U.S. in 1960, LEGO has been a perennial bestseller, but over the past year-and-a-half, sales have exploded. (Again, not literally.) While many companies have been badly hurt by the current economy, LEGO achieved 38 percent growth last year, and has continued to grow this year.

What’s made this success? Well, successful toys have always mirrored what’s going on in the culture, and in many toy categories that’s meant having toys that feature popular characters and themes from entertainment. Believe it or not, only 12 years ago that LEGO didn’t have any brick sets based on movies, TV shows or characters. Today, much of the company’s success has been with Star Wars, Spongebob, and Thomas the Tank Engine. In addition to providing the fun and imagination of open-ended building, these themes and characters provide fertile ground for creative play—and kids naturally want them. Last year, the Indiana Jones LEGO sets were some of the best sellers ever for the company.

Typically, older kids migrate into more sophisticated building sets, such as LEGO’s Mindstorms or other robotics, but that’s a comparatively small group versus the kids who just love to build. MEGA broke new ground this year with an introduction of a line of construction blocks based on the hit video game, Halo. What’s significant about this is that “conventional wisdom” would say that kids who like games like Halo aren’t going to want to play with blocks. So far, sales are proving that very wrong. In fact, as has been demonstrated in other categories—notably collectibles, comics and cards—people who are into a franchise such as Halo are very likely to want to have a “Halo experience” with other kinds of products. What raised a few eyebrows when it was launched has now got lots of companies thinking about what the next big hit is going to be.

The appeal of construction toys for kids has always been the build-play-display experience. Whether a child is imaginatively reenacting an adventure from the Isle of Sodor with Thomas or imagining the next fighting ship for Halo, these toys fire the creative spirit in virtually anyone—making a great pastime and delivering lots of fun. These toys have enduring appeal precisely because they are not electronic and because they engage a different part of the imagination (and the brain) than other types of play. Having that balance with themes that are appealing to various different sets of consumers helps keep a classic play pattern very contemporary. And that’s what this has all been building up to.